The present invention relates to a safety arrangement for preventing the unauthorized opening of a housing, in which wall parts are connected flange-like or cover-like with each other and are riveted together by at least one safety rivet made of a harder material than the material of at least one of the connected wall parts and removable only by destruction, as are known, for example, with screwless multi-contact sockets in extension cables for the home use.
Other technically more demanding industrial products are frequently also secured against unauthorized opening by such types of safety arrangements, whereby added thereto is the purpose of the ability to indicate any unauthorized tampering which, nonetheless, has taken place. Warranty claims against the respective manufacturer are regularly asserted improperly by any such unauthorized tampering or intervention because the manufacturer cannot be held responsible for manipulations that have taken place after the unauthorized opening of the apparatus. In certain cases, great consequential damages can be avoided by a completely satisfactory functioning of the apparatus enclosed by the housing parts which might otherwise occur in case of an unauthorized manipulation under certain circumstances; incalculable liability claims may be asserted against the manufacturer by reason of the product liability, which the manufacturer can defeat only in the case of a completely satisfactory indication of a manipulation. The reasons for such manipulations are in part unknown; however, it is a fact that they occur.
In a prior art riveting arrangement of the housing parts, the rivets were drilled out for opening the housing and the parts were again properly closed during the closing of the apparatus by commercially available rivets so that an indication of a manipulation or tampering was not possible. Frequently such housing parts are also screwed together and the screws are secured by an appropriate sealing material such as lacquer. However, also in such a case it is not always possible to indicate an unauthorized opening of the housing because after a careful removal of the old sealing lacquer residues and after an application of a new sealing lacquer of the same quality, the apparatus can again be sealed properly. The use of a seal, such as a lead seal or plaster seal, does not provide a certain indication of any possible unauthorized opening because a seal may also be torn off occasionally by inattention when working in the proximity of such an apparatus.
It is conceivable to glue together the housing parts with each other in such a manner that they can be opened only destructively in every case; however, in that case no authorized service or maintenance operations in connection with the parts enclosed by the housing are then possible. The same is also true for a welded connection of the housing parts which would be possible in the case of a construction of the two housing parts of thermoplastic synthetic resinous material.
It is the object of the present invention to so construct the safety arrangement of the aforementioned type that in every case of an unauthorized opening of the housing parts such an intervention or tampering can be indicated with certainty.
The underlying problems are solved according to the present invention in that with a construction of the housing parts of aluminum and/or plastic materials, the safety rivet consists of a preferably alloyed steel, and in that the rivet end is peened over loosely, though without play, in such a manner that the peened-over safety rivet is easily rotatable. Owing to the great material hardness of the safety rivet compared to the hardness of the housing material, the rivet cannot be removed tracelessly and replaced during the closing of the housing by a new safety rivet of the same type; instead, by reason of the great hardness of the safety rivet, scoring traces or grinding traces can be recognized at the housing walls, insofar as the safety rivet can be removed at all. More particularly, an appropriate constructional realization provides that the safety rivet consisting of alloyed steel is riveted only loosely so that it rotates in the rivet hole during the attempt of drilling it out and therefore cannot be drilled out. By reason of the recessed or countersunk arrangement of the rivet ends, the rivet cannot be held fast by means of pliers.